Preparing chamois leather



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Patented Nov. 15, 1938 PATENT OFFICE I 2.13am momma OHAMOIS LEATHER Georges Robert Gasnler, La Sure, France, as-

aignor to Jacques Wolf 8; Company, Passaic,

N. L, a corporation of New Jersey No Drawing. Application December 12, 1936, Serial No. 115,586

.4 Claims. (01. 1494) I The usual method of tanning hides or skins (hereinafter termed "sklns) of deer, sheep and the like so as to impart thereto a chamois leather character consists in impregnating the skins with some tanning oils, as fish oil, working them in a beating machine, stacking them in piles followed by exposure to air to oxidize the oil and repeating these steps a number of times in a gradually rising temperature, after which they are soaked in water, pressed and ole-greased or deprived of tree oil, which oil thus reclaimed is incidentally mown by the French term "moelli-m.

n the other hand, it is known to tan skins by what is termed the "chrome" method. For instance, by what is known as the two-hath procedure the skins are first soaked in an acidchrome bath, as a mixture including sodium or potassium bichromate solution and acid, such, as sulphuric acid, and then they are soaked in an acid bath containing a reducing agent, tor example, hyposulphite or bisulphite, the resulting chromic oxide combining with the fiber.

en the first-named or oil treatment is iollowed, whereas the skins have oi course the soft and other qualities characterizing ohamois leather they are unfavorably affected by boiling water. en the second-named or chrome tanning treatment is followed the skins withstand the in- :duence oi boiling water but of course they do not have the character of chamois leather.

l have found that it is possible to combine steps or these two treatments and thereby produce skins having not only a remarkable degree or softness, together with other qualities eharacterirzlng or desired in good chamois leather, but also resistance to boiling water, and that by my procedure there will also ensue other advantageous results, notably a very great saving in time to complete the treatment; a reclamation of a very considerable nuantlty oi moellen" of first quality; and the possibility of dyeing without dilliculty and according to any of the lmown processes and oi. finishing the skins directly or re-tannlng them to suit the particular service for which they are intended. Either split or grain skins may be treated. My invention also makes it possible to treat other skins, such as calf and goat, so as to give them superior softness and other qualities tending to make them simulate chamois leather.

, In carrying out my invention I impregnate the skins with an acid-dichromate solution (as one containing sodium or potassium 'bichromate and sulphuric acid) and a tanning oil, they being present in the skins with each other. In other words there ensues reduction of the chromic acid with oxidation of the oil, whereby the resulting chromic oxide makes the skins resistant to boiling water while the oxidized oil serves to impart the. softness and other qualities characterizing chamois leather.

Following are examples oi procedures which may be followed in the practice of my invention:

1. The skins, already given the usual lime or putreiactive treatment, are first treated and thus made to be impregnated by a solution of, for example, sodium bichromate and 2% sulphuric acid, these proportions being by weight of the moist skins. Next, the skins while still moist with said solution are made to be impregnated in some way by a tanning oil, as fish oil, and usually, to obtain impregnation, this will be done with the assistance of some liquid agent mixed with the tanning oil, or for example as follows: While so moist they are treated in a drum with a mixture of 25% ordinary fish oil or other tanning oil and more or less emulsified fish oil as an agent to assist penetration (or this agent may be some other emulsified tanning oil, sulphonate alcohol,

lecithin, a preparation of triethanolamine, or a 2 colloid), the last-named proportions being also by weight of the moist skins. The skins are then stacked or piled, dried in the air, and ole-greased with a suitable solvent or an aqueous medium containing an alkaline agent, or both, according tothe usual practice. The time in which the skins are subjected to the action oi each liquid is such that adequate penetration will ensue, or about twenty-four hours in the case of the first and a few hours in the case of the second liquid.

2. Or I may follow Example No. l. but blow air through the drum while gradually raising the temperature therein to 50 C.

3. 0r between the acid-dichromate and oil treatments of Example No. 1 I may subject the skins to a slight pre-reduotion by impregnating them with some reducing agent, as hyposulphite.

4. Or after the oil treatment I may subject the skins to a slight after-reduction by impregnating them with such a reducing agent.

What is essential according to my invention is that while the skins are still moist or charged with the acid-dlchromate solution, they are made to be impregnated in some way by the tanning oil. In practice," however, I have found it more expedient to accomplish this with the aid of some liquid medium whereby the oil will impregnate the skins notwithstanding the pro-existence therein of said solution.

Having thus fully described my invention what I claim is:

15 impregnation or the skins by the oil.

3. The method oi treating skins to impart thereto a chamois leather character and render them resistant to boiling water which consists in first impregnating the skins with an acidified diohromate solution for about twenty-four hours and then impregnating the skins in the presence 01 such solution with tanning oil.

4. The method 01 treating skins to impart thereto a chamois leather character and render them resistant to boiling water which consists in first impregnating the skins with an acidified dichromate solution for about twenty-four hours and then impregnating the skins in the presence of such solution with a mixture of tanning oil' and a medium to assist impregnation oi the skins by the oil.

GEORGES ROBERT GASNIER. 

